You’ve probably heard of influencers, that group of internet-famous people who have more than 1 million social media followers and can make big money by plugging various brands. And you may have even heard of microinfluencers, who do the same thing for a still sizable but somewhat smaller social media audience — from the tens to low hundreds of thousands.

Now get ready for the nanoinfluencers.

That is the term (“nanos” for short) used by companies to describe people who have as few as 1,000 followers and are willing to advertise products on social media.

Their lack of fame is one of the qualities that make them approachable. When they recommend a shampoo or a lotion or a furniture brand on Instagram, their word seems as genuine as advice from a friend.

Brands enjoy working with them partly because they are easy to deal with. In exchange for free products or a small commission, nanos typically say whatever companies tell them to.

With roughly 2,600 Instagram followers, Alexis Baker, 25, had a relatively ordinary social media presence, with photos of fashionable outfits and tropical vacation spots filling her feed. But her online persona changed when she started praising products like Suave Professionals Rose Oil Infusion shampoo, Clinique Beyond Perfecting foundation and concealer, and Loco Coffee, a mix of cold brew and coconut water.

People who know Baker were surprised when the hashtags used to denote advertisements — #sponsored and #ad — started popping up on her account. They were also a little impressed that she was Instagramming like an influencer.

“My friends were like: ‘Wait a minute — you don’t have tens of thousands of followers. How did you get contacted about this?’ ” Baker said. “I didn’t really have an answer for them.”

A leasing manager in Alexandria, Va., Baker stumbled into the hobby-slash-gig after being scouted by Obviously, which describes itself as “a full-service influencer marketing agency.”

To Mae Karwowski, chief executive of Obviously, nanoinfluencers are a largely untapped and inexpensive opportunity.

“Everyone who’s on Instagram has that friend who is just really popular and is racking up ‘likes’ and comments and has great content,” said Karwowski, who defined nanoinfluencers as people with roughly 1,000 to 5,000 Instagram followers. “They’ve probably never worked with a brand before, but they’re just really good at social media.”

The influencer economy is opaque — and rife with questionable tactics — but there’s no doubt it attracts big money. A reminder of that came recently when a public relations firm sued 20-year-old fashion model Luka Sabbat, saying he failed to fulfill the terms of an agreement with Snap Spectacles. According to the suit, Sabbat was offered $60,000 for providing one Instagram post and three Instagram Stories and for being photographed during fashion weeks while wearing the spectacles.

But for most nanoinfluencers, money isn’t part of the deal. Free products are viewed as fair compensation for the ads they post.

“If it does happen to blow up and take off full time, then great,” Baker said. “But that is not what I’m looking for at all. It’s just something I love doing.

Kelsey Rosenberg, a 26-year-old in Columbus, Ohio, with 1,900 Instagram followers, saw an opportunity when influencer marketing took off. She contacted companies, including bars and restaurants in her area, and now regularly incorporates advertising into her Instagram feed.

“It’s like one of your friends selling you a new skin care product is amazing, but instead of me telling my friends at happy hour, it’s me telling them on Instagram,” she said.

Krishna Subramanian, a founder of Captiv8, another influencer marketing firm, said he was skeptical about brands marketing their wares through people with unremarkable social media followings.

“Are they able to actually measure something out of it and say, ‘This is successful, we want to do more of it’?” he asked.

But Karwowski, of Obviously, said she was confident in the strategy. Her firm has 7,500 nanoinfluencers in its database, she said, and it plans to double that number by March.

“The youngest generation has grown up with this technology, so they’re very accustomed to seeing people talk about products they like and are recommending, so now there is a new willingness for them to participate in that,” Karwowski said.

She added, “You’re able to place a lot of really small bets rather than, ‘We’re going to work with Kim Kardashian.’ ”